1. Technical Field
The present invention relates to a sensor unit array, a Raman spectroscopic device, and an electronic apparatus.
2. Related Art
In recent years, surface enhanced Raman Scattering (SERS) using a localized surface plasmon resonance (LSPR) has attracted attention as a spectroscopic technology for detecting low-concentration target molecules at high sensitivity. The SERS is a phenomenon in which an enhanced electric field is formed on a metal surface having nanometer-scale structures, and the Raman scattering light is enhanced by 102 through 1014 times by the enhanced electric field. When excitation light such as a laser beam is applied in the state in which a substance to be the target is adsorbed on such a metal surface as described above, light (Raman scattering light) having a wavelength slightly shifted from the wavelength of the excitation light is scattered as much as the vibration energy of the substance (molecules). By performing a spectroscopic process on the scattering light, a spectrum (fingerprint spectrum) specific to the type (molecular species) of the substance can be obtained. By using the SERS, the position and the shape of the fingerprint spectrum can be analyzed at high sensitivity, and it becomes possible to qualitatively and quantitatively detect the substance at extremely high sensitivity.
The sensor having such a metal surface can provide highly sensitive measurement, and can be extremely miniaturized at the same time. However, the easiness of handling by the user is impaired by miniaturizing the sensor in some cases, and JP-A-2001-330560, for example, discloses an attempt to enhance the handling easiness by putting a plurality of measuring chips in a housing called cassette.
In general, in the chips used for the SERS, the measurement is performed by collecting a laser beam to have a spot of several micrometers through several hundred micrometers with a lens with respect to a structure having arranged nanoparticles of noble metal such as gold or silver. Therefore, if the chip is used as a sensor chip, it is sufficient for the chip to have a planar size of about 3 mm on a side.
Further, in particular in the purpose of taking and then analyzing a biological gas such as an exhaled gas or a skin gas, the chip is always exposed to a high-humidity environment. In this case, even if the contact of the moisture with the chip is reduced using a moisture removing filter or the like, a small amount of water molecules continues to be adsorbed on the metal surface of the chip. Therefore, the entire metal surface is covered with the water molecules if it is used for several days, for example, and the adsorption of the target molecules is hindered in some cases. Therefore, under such circumstances, it is necessary to replace the sensor chip at a higher frequency.
Therefore, in order to realize the detection device which is small in size and high in sensitivity, and can easily be used by the user at any location, it is necessary to make it easy to replace such a small sensor chip.
JP-A-2001-330560 described above fails to disclose anything about storage, deterioration, and so on of the chips although there is a description that the chips are housed in the cassette to enhance the handling easiness. Further, since it results that a separate configuration such as the cassette from the chips is added, it cannot necessarily be said that both of the miniaturization and the handling easiness are sufficiently achieved.